This invention relates to road surfacing machines in general and in particular to those machines capable of planing a road surface to a level of desired flatness.
Roadways and runways are generally built to construction specifications which define the maximum amount of vertical deviation from a reference plane over a given longitudinal distance, for example, 7 inches of vertical deviation over a mile of length. If, after the roadway or runway is built, the deviation is found to be greater than the maximum allowed, the higher portions must be ground down or planed to bring the construction to within specifications. Considering the small amount of deviation required, it is obvious that close control of the cut made by a road planing machine is necessary.
Major deficiencies in prior art road planing devices include the lack of such control and the related inability to keep the cutter head penetrating to the desired depth for proper surface finish. This often occurs when the machine is not capable of transferring enough controlled weight to the cutter head while maintaining the desired longitudinal (forward) speed. Another deficiency in prior art devices is the inability to accurately and reliably blend or "feather" cuts into each other using the adjacent prior cut as a reference.